Sample selection protocol:
Stationary trips
Complete checklists (report all species)
Drop duplicates from group trips.
Drop trips with 1 bird
Duration between 5-240 mins
Overall Notes
Results are sensitive to sample selection criteria (num cities, number days pre/post, home, lockdown date)
We select cities first, and then users. This gives us the same users in each pre/post period (in 2020) with the caveat that users mobility is limited to the top X cities.
Diff-in-diff results consistently positive and strong. Event study somewhat unstable depending on lockdown day. Why is DID counterfactual better?
Summary Stats for 2020 including users who participated in at least 2 days before and after lockdown.
This is the subset of eBird observations meeting the pariticipation criteria in the top 20 Indian cities by population size. Note that not all top 20 cities may be present in eBird.
| COUNTY | STATE | POP_DENSITY |
|---|---|---|
| North East Delhi | Delhi | 36155.2258 |
| Central Delhi | Delhi | 27729.5238 |
| East Delhi | Delhi | 27132.4762 |
| Chennai | Tamil Nadu | 26552.7543 |
| Kolkata | West Bengal | 24306.4541 |
| Mumbai Suburban | Maharashtra | 20979.7354 |
| Mumbai | Maharashtra | 19652.2994 |
| West Delhi | Delhi | 19563.4077 |
| South Delhi | Delhi | 11060.4413 |
| South West Delhi | Delhi | 5446.4561 |
| Bangalore | Karnataka | 4381.3985 |
| New Delhi | Delhi | 4057.2571 |
| Haora | West Bengal | 3306.0866 |
| North 24 Parganas | West Bengal | 2444.9880 |
| Chandigarh | Chandigarh | 909.1664 |
| Hyderabad | Telangana | 706.8919 |
| Puducherry | Puducherry | 480.7997 |
| PREPOST | Num. Trips | Num. Cities | Num. Users | Num. Species |
|---|---|---|---|---|
| Before | 3561 | 180 | 351 | 673 |
| After | 10788 | 139 | 351 | 625 |
| PREPOST | Num. Trips | Num. Cities | Num. Users | Num. Species |
|---|---|---|---|---|
| Before | 753 | 17 | 74 | 205 |
| After | 2343 | 15 | 74 | 236 |
This table shows trip-level statistics before and after lockdown.
| PREPOST | Trip Length | Mean Species Richness | Median Species Richness |
|---|---|---|---|
| Before | 24.16007 | 12.07638 | 10 |
| After | 22.63969 | 12.37671 | 11 |
| PREPOST | Trip Length | Mean Species Richness | Median Species Richness |
|---|---|---|---|
| Before | 19.86587 | 10.56574 | 9 |
| After | 22.57192 | 12.28937 | 11 |
Marginal species are species observed after lockdown which were not observed before lockdown. To implement: in each city, obtain list of species observed (across all users) in before and after lockdown. Extract species in “after” list not in “before” list, and collect in a data frame. If fewer species after, city will not be in final list.
| COMMON.NAME | SCIENTIFIC.NAME | COUNTY |
|---|---|---|
| white egret sp. | Ardea/Egretta/Bubulcus sp. | Kolkata |
| falcon sp. | Falco sp. | Kolkata |
| swift sp. | Apodidae sp. | Kolkata |
| Gray-headed Swamphen | Porphyrio poliocephalus | Kolkata |
| Rufous Woodpecker | Micropternus brachyurus | Kolkata |
| Fulvous-breasted Woodpecker | Dendrocopos macei | Kolkata |
| Scaly-breasted Munia | Lonchura punctulata | Kolkata |
| Little Egret | Egretta garzetta | Kolkata |
| Paddyfield Pipit | Anthus rufulus | Kolkata |
| Asian Openbill | Anastomus oscitans | Kolkata |
| Zitting Cisticola | Cisticola juncidis | Kolkata |
| Spotted Owlet | Athene brama | Kolkata |
| Oriental Honey-buzzard | Pernis ptilorhynchus | Kolkata |
| Eurasian Moorhen | Gallinula chloropus | Kolkata |
| Red-breasted Parakeet | Psittacula alexandri | Kolkata |
| House Crow | Corvus splendens | West Delhi |
| Laughing Dove | Streptopelia senegalensis | West Delhi |
| Indian White-eye | Zosterops palpebrosus | West Delhi |
| Common Myna | Acridotheres tristis | West Delhi |
| Rose-ringed Parakeet | Psittacula krameri | West Delhi |
| Asian Koel | Eudynamys scolopaceus | West Delhi |
| Jungle Babbler | Turdoides striata | West Delhi |
| Alexandrine Parakeet | Psittacula eupatria | West Delhi |
| prinia sp. | Prinia sp. | West Delhi |
| Black Drongo | Dicrurus macrocercus | West Delhi |
| Indian Silverbill | Euodice malabarica | Bangalore |
| Yellow-eyed Babbler | Chrysomma sinense | Bangalore |
| swift sp. | Apodidae sp. | Bangalore |
| ibis sp. | Threskiornithidae sp. (ibis sp.) | Bangalore |
| parakeet sp. | Psittaciformes sp. (parakeet sp.) | Bangalore |
| Greater Spotted Eagle | Clanga clanga | Bangalore |
| Ashy Woodswallow | Artamus fuscus | Bangalore |
| Pied Kingfisher | Ceryle rudis | Bangalore |
| Eurasian Spoonbill | Platalea leucorodia | Bangalore |
| bird sp. | Aves sp. | Bangalore |
| Lonchura sp. | Lonchura sp. | Bangalore |
| stork sp. | Ciconiidae sp. | Bangalore |
| cormorant sp. | Phalacrocoracidae sp. | Bangalore |
| Oriental Honey-buzzard | Pernis ptilorhynchus | Bangalore |
| Garganey | Spatula querquedula | Bangalore |
| Black-rumped Flameback | Dinopium benghalense | Bangalore |
| White-naped Woodpecker | Chrysocolaptes festivus | Bangalore |
| Blue-throated Flycatcher | Cyornis rubeculoides | Bangalore |
| bee-eater sp. | Merops sp. | Bangalore |
| prinia sp. | Prinia sp. | Bangalore |
| Red-naped Ibis | Pseudibis papillosa | Bangalore |
| Blue-faced Malkoha | Phaenicophaeus viridirostris | Bangalore |
| flowerpecker sp. | Prionochilus/Dicaeum sp. | Bangalore |
| eagle sp. | Accipitridae sp. (eagle sp.) | Bangalore |
| duck sp. | Anatinae sp. | Bangalore |
| Blyth’s Pipit | Anthus godlewskii | Bangalore |
| Eurasian Coot | Fulica atra | Bangalore |
| Indian Nightjar | Caprimulgus asiaticus | Bangalore |
| Black-naped Monarch | Hypothymis azurea | Bangalore |
| Indian Pitta | Pitta brachyura | Bangalore |
| Indian Blue Robin | Larvivora brunnea | Bangalore |
| Yellow Bittern | Ixobrychus sinensis | Bangalore |
| Black/Ashy Drongo | Dicrurus macrocercus/leucophaeus | Bangalore |
| Common Rosefinch | Carpodacus erythrinus | South Delhi |
| Rosy Starling | Pastor roseus | South Delhi |
| Phylloscopus sp. | Phylloscopus sp. | South Delhi |
| Sulphur-bellied Warbler | Phylloscopus griseolus | South Delhi |
| Little Swift | Apus affinis | South Delhi |
| Red-breasted Flycatcher | Ficedula parva | South Delhi |
| Lesser Whitethroat | Sylvia curruca | South Delhi |
| Greenish Warbler | Phylloscopus trochiloides | South Delhi |
| Cattle Egret | Bubulcus ibis | South Delhi |
| Yellow-crowned Woodpecker | Leiopicus mahrattensis | South Delhi |
| crow sp. | Corvus sp. (crow sp.) | South Delhi |
| parakeet sp. | Psittaciformes sp. (parakeet sp.) | South Delhi |
| Large Gray Babbler | Turdoides malcolmi | South Delhi |
| Indian Robin | Copsychus fulicatus | South Delhi |
| House Sparrow | Passer domesticus | South Delhi |
| Indian Silverbill | Euodice malabarica | Mumbai |
| Rosy Starling | Pastor roseus | Mumbai |
| Jungle Babbler | Turdoides striata | Mumbai |
| Phylloscopus sp. | Phylloscopus sp. | Mumbai |
| Little Stint | Calidris minuta | Mumbai |
| Shikra | Accipiter badius | Mumbai |
| Asian Openbill | Anastomus oscitans | Mumbai |
| Peregrine Falcon | Falco peregrinus | Mumbai |
| Purple Sunbird | Cinnyris asiaticus | Mumbai |
| Indian Cormorant | Phalacrocorax fuscicollis | Mumbai |
| wagtail sp. | Motacilla sp. | Mumbai |
| Brahminy Kite | Haliastur indus | Mumbai |
| white egret sp. | Ardea/Egretta/Bubulcus sp. | Mumbai |
| swift sp. | Apodidae sp. | Mumbai |
| Glossy Ibis | Plegadis falcinellus | Mumbai |
| Spotted Owlet | Athene brama | Mumbai |
| Bank Myna | Acridotheres ginginianus | Mumbai |
| ibis sp. | Threskiornithidae sp. (ibis sp.) | Mumbai |
| Little Swift | Apus affinis | North 24 Parganas |
| Common Iora | Aegithina tiphia | North 24 Parganas |
| Lesser Whistling-Duck | Dendrocygna javanica | North 24 Parganas |
| Ashy Woodswallow | Artamus fuscus | North 24 Parganas |
| Great Egret | Ardea alba | North 24 Parganas |
| Asian Koel | Eudynamys scolopaceus | Chandigarh |
| Indian Gray Hornbill | Ocyceros birostris | Chandigarh |
| Black-rumped Flameback | Dinopium benghalense | Chandigarh |
| Yellow-footed Green-Pigeon | Treron phoenicopterus | Chandigarh |
| Red Junglefowl | Gallus gallus | Chandigarh |
| Laughing Dove | Streptopelia senegalensis | Chandigarh |
| Asian Palm-Swift | Cypsiurus balasiensis | Mumbai Suburban |
| Indian Golden Oriole | Oriolus kundoo | Mumbai Suburban |
| Indian Robin | Copsychus fulicatus | Mumbai Suburban |
| Red-vented Bulbul | Pycnonotus cafer | Mumbai Suburban |
| Thick-billed Flowerpecker | Dicaeum agile | Mumbai Suburban |
| Laughing Dove | Streptopelia senegalensis | Mumbai Suburban |
| Gray/Purple Heron | Ardea cinerea/purpurea | Chennai |
| drongo sp. | Dicrurus sp. | Chennai |
| Black/Ashy Drongo | Dicrurus macrocercus/leucophaeus | Chennai |
| Spotted Dove | Streptopelia chinensis | Chennai |
| Great Cormorant | Phalacrocorax carbo | Chennai |
| crow sp. | Corvus sp. (crow sp.) | Chennai |
| sunbird sp. | Nectariniidae sp. (sunbird sp.) | Chennai |
| Common Tern | Sterna hirundo | Chennai |
| owl sp. | Strigiformes sp. | Chennai |
| Orange-headed Thrush | Geokichla citrina | Chennai |
| Red-whiskered Bulbul | Pycnonotus jocosus | Chennai |
| Plain Prinia | Prinia inornata | Chennai |
| Indian Silverbill | Euodice malabarica | Chennai |
| tern sp. | Sterninae sp. | Chennai |
| Western Yellow Wagtail | Motacilla flava | Chennai |
| Pied Kingfisher | Ceryle rudis | Chennai |
| Asian Openbill | Anastomus oscitans | Chennai |
| Ashy Prinia | Prinia socialis | Chennai |
| Asian Pied Starling | Gracupica contra | Chennai |
| Black Bittern | Ixobrychus flavicollis | Chennai |
| Little Swift | Apus affinis | Chennai |
| Rosy Starling | Pastor roseus | South West Delhi |
| Indian Golden Oriole | Oriolus kundoo | South West Delhi |
| old world warbler sp. | Passeriformes sp. (Old World warbler sp.) | South West Delhi |
| duck sp. | Anatinae sp. | South West Delhi |
| Common Chiffchaff | Phylloscopus collybita | South West Delhi |
| Little Swift | Apus affinis | South West Delhi |
| Long-tailed Shrike | Lanius schach | South West Delhi |
| Eurasian Hoopoe | Upupa epops | South West Delhi |
| Egyptian Vulture | Neophron percnopterus | South West Delhi |
| Oriental Honey-buzzard | Pernis ptilorhynchus | South West Delhi |
| Booted Eagle | Hieraaetus pennatus | South West Delhi |
| drongo sp. | Dicrurus sp. | South West Delhi |
| Gray Heron | Ardea cinerea | South West Delhi |
| Great Cormorant | Phalacrocorax carbo | South West Delhi |
| Short-toed Snake-Eagle | Circaetus gallicus | South West Delhi |
| Blyth’s Reed Warbler | Acrocephalus dumetorum | South West Delhi |
| Brown Rock Chat | Oenanthe fusca | South West Delhi |
| Rufous Treepie | Dendrocitta vagabunda | East Delhi |
| Indian Robin | Copsychus fulicatus | East Delhi |
| Red-whiskered Bulbul | Pycnonotus jocosus | East Delhi |
| White Wagtail | Motacilla alba | East Delhi |
| Green Bee-eater | Merops orientalis | East Delhi |
| Striated Babbler | Turdoides earlei | East Delhi |
| Purple Heron | Ardea purpurea | East Delhi |
| Indian Pond-Heron | Ardeola grayii | East Delhi |
| Greater Coucal | Centropus sinensis | East Delhi |
| Hume’s Warbler | Phylloscopus humei | East Delhi |
| Indian Spot-billed Duck | Anas poecilorhyncha | East Delhi |
| Indian Peafowl | Pavo cristatus | East Delhi |
| ibis sp. | Threskiornithidae sp. (ibis sp.) | East Delhi |
| Woolly-necked Stork | Ciconia episcopus | East Delhi |
| White-throated Kingfisher | Halcyon smyrnensis | East Delhi |
| Black-rumped Flameback | Dinopium benghalense | East Delhi |
| Little Egret | Egretta garzetta | East Delhi |
| Shikra | Accipiter badius | East Delhi |
| passerine sp. | Passeriformes sp. | East Delhi |
| Indian Cormorant | Phalacrocorax fuscicollis | East Delhi |
| swift sp. | Apodidae sp. | East Delhi |
| Green Sandpiper | Tringa ochropus | East Delhi |
| Indian Golden Oriole | Oriolus kundoo | East Delhi |
| Little Swift | Apus affinis | East Delhi |
| Indian Spotted Eagle | Clanga hastata | East Delhi |
| Egyptian Vulture | Neophron percnopterus | East Delhi |
| Great Cormorant | Phalacrocorax carbo | East Delhi |
| Gray Heron | Ardea cinerea | East Delhi |
| Red-breasted Flycatcher | Ficedula parva | East Delhi |
| Indian Gray Hornbill | Ocyceros birostris | East Delhi |
| Lesser Whitethroat | Sylvia curruca | East Delhi |
| Coppersmith Barbet | Psilopogon haemacephalus | North East Delhi |
| Rose-ringed Parakeet | Psittacula krameri | North East Delhi |
| Asian Koel | Eudynamys scolopaceus | North East Delhi |
| Large Gray Babbler | Turdoides malcolmi | North East Delhi |
| Brown-headed Barbet | Psilopogon zeylanicus | North East Delhi |
| Rock Pigeon | Columba livia | North East Delhi |
| Gray Heron | Ardea cinerea | Puducherry |
| Barn Owl | Tyto alba | Puducherry |
| sunbird sp. | Nectariniidae sp. (sunbird sp.) | Puducherry |
| Indian Thick-knee | Burhinus indicus | Puducherry |
| Indian Golden Oriole | Oriolus kundoo | Puducherry |
| Black-headed Ibis | Threskiornis melanocephalus | Puducherry |
| Painted Stork | Mycteria leucocephala | Puducherry |
| passerine sp. | Passeriformes sp. | Puducherry |
| Green Bee-eater | Merops orientalis | Puducherry |
| Red-necked Falcon | Falco chicquera | Puducherry |
| White-browed Wagtail | Motacilla maderaspatensis | Puducherry |
| Intermediate Egret | Ardea intermedia | Puducherry |
| Eurasian Spoonbill | Platalea leucorodia | Puducherry |
| white egret sp. | Ardea/Egretta/Bubulcus sp. | Puducherry |
| Lonchura sp. | Lonchura sp. | Puducherry |
| duck sp. | Anatinae sp. | Puducherry |
| Great Egret | Ardea alba | Puducherry |
| heron sp. | Ardeidae sp. | Puducherry |
| harrier sp. | Circus sp. | Puducherry |
| Garganey | Spatula querquedula | Puducherry |
| Clamorous Reed Warbler | Acrocephalus stentoreus | Puducherry |
| Pied Bushchat | Saxicola caprata | Puducherry |
| Rosy Starling | Pastor roseus | Puducherry |
| Black Kite | Milvus migrans | Puducherry |
| Black-winged Kite | Elanus caeruleus | Puducherry |
| Gray-headed Swamphen | Porphyrio poliocephalus | Puducherry |
| wagtail sp. | Motacilla sp. | Puducherry |
| Indian Robin | Copsychus fulicatus | Puducherry |
| Pin-tailed Snipe | Gallinago stenura | Puducherry |
| Indian Roller | Coracias benghalensis | Puducherry |
| Common Kingfisher | Alcedo atthis | Puducherry |
| Little Egret | Egretta garzetta | Puducherry |
| Asian Openbill | Anastomus oscitans | Puducherry |
| swallow sp. | Hirundinidae sp. | Puducherry |
| diurnal raptor sp. | Accipitriformes/Falconiformes sp. | Puducherry |
| tern sp. | Sterninae sp. | Puducherry |
| Wood Sandpiper | Tringa glareola | Puducherry |
| Indian Cormorant | Phalacrocorax fuscicollis | Puducherry |
| snipe sp. | Gallinago sp. | Puducherry |
| Paddyfield Pipit | Anthus rufulus | Puducherry |
| Plain Prinia | Prinia inornata | Puducherry |
| Oriental Darter | Anhinga melanogaster | Puducherry |
| Tickell’s Blue Flycatcher | Cyornis tickelliae | Hyderabad |
| Thick-billed Flowerpecker | Dicaeum agile | Hyderabad |
| Large-billed Crow | Corvus macrorhynchos | Hyderabad |
| swallow sp. | Hirundinidae sp. | Hyderabad |
| Rufous Treepie | Dendrocitta vagabunda | Hyderabad |
| Cattle Egret | Bubulcus ibis | Hyderabad |
| Indian Peafowl | Pavo cristatus | Hyderabad |
| Thick-billed/Pale-billed Flowerpecker | Dicaeum agile/erythrorhynchos | Hyderabad |
| Barn Swallow | Hirundo rustica | Hyderabad |
| Indian Gray Hornbill | Ocyceros birostris | Hyderabad |
| White-browed Wagtail | Motacilla maderaspatensis | Hyderabad |
| Gray-bellied Cuckoo | Cacomantis passerinus | Hyderabad |
| Glossy Ibis | Plegadis falcinellus | Hyderabad |
| Dusky Crag-Martin | Ptyonoprogne concolor | Hyderabad |
| Rosy Starling | Pastor roseus | Hyderabad |
| River Tern | Sterna aurantia | Hyderabad |
| parakeet sp. | Psittaciformes sp. (parakeet sp.) | Hyderabad |
| Indian Robin | Copsychus fulicatus | Hyderabad |
| Eurasian Kestrel | Falco tinnunculus | Hyderabad |
| Little Egret | Egretta garzetta | Hyderabad |
| diurnal raptor sp. | Accipitriformes/Falconiformes sp. | Hyderabad |
| Indian Pond-Heron | Ardeola grayii | Hyderabad |
| Western Yellow Wagtail | Motacilla flava | Hyderabad |
| Gray Wagtail | Motacilla cinerea | Hyderabad |
| Indian Pond-Heron | Ardeola grayii | Haora |
| Jungle Babbler | Turdoides striata | Haora |
| Jungle Myna | Acridotheres fuscus | Haora |
| Blue-throated Flycatcher | Cyornis rubeculoides | Haora |
| Barn Swallow | Hirundo rustica | Haora |
| Large-billed Leaf Warbler | Phylloscopus magnirostris | Haora |
| Green-crowned Warbler | Phylloscopus burkii | Haora |
| Blyth’s Reed Warbler | Acrocephalus dumetorum | Haora |
| Intermediate Egret | Ardea intermedia | Haora |
| Large-billed Crow | Corvus macrorhynchos | Haora |
| Eurasian Collared-Dove | Streptopelia decaocto | Haora |
| Asian Palm-Swift | Cypsiurus balasiensis | Haora |
| Purple-rumped Sunbird | Leptocoma zeylonica | Haora |
| Black-crowned Night-Heron | Nycticorax nycticorax | Haora |
| Asian Brown Flycatcher | Muscicapa dauurica | Haora |
| Cattle Egret | Bubulcus ibis | Haora |
| Greenish Warbler | Phylloscopus trochiloides | Haora |
| Greater Coucal | Centropus sinensis | Haora |
We estimate:
\[ SR_{ijtd} = \sum_{e=-24, e\neq0}^{24} 1(t-LD=e)\beta_{e} + X_{ijdt} + \gamma_{t} + \mu_{d} + \epsilon_{ijtd}\] where \(SR_{ijtd}\) is species richness observed by user i on trip j on date t in district d. Each coefficient \(\beta_{e}\) captures species richness relative to the day of lockdown (LD). In the preferred specification, LD = March 24, 2020 and this date is normalized to zero and omitted so that it describes the reference period. If the timing of lockdown is exogenous to pre-period outcomes, then \(\beta_{e}\) should be zero for all \(e<0\). \(\gamma_{t}\) are a set of temporal controls and include date fixed effects and hour fixed effects. \(\mu_{d}\) are city fixed effects. \(X_{ijdt}\) is a vector of controls and includes: duration of trip and user \(i\)’s experience, measured as the number of trips he/she has taken since January 2019.
Notes:
We see action around pilot lockdown, not as much around official lockdown. Suggests people responded to the former.
We start seeing increases in species diversity post-lockdown when we narrow in on urban environments. As we increase allowable cities, this adds population-sparse places so the effect is dampned.
Larger increases in post-lockdown species diversity as we increase the participation constraint (e.g. 10 days before/after curfew)
data: number of times each user sees each species before and after lockdown. interpretation: proportion of user base seeing different frequencies of species.
In this specification, we aim to estimate the difference in species richness per trip before and after lockdown, compared to same difference in 2019. In other words, we subtract the change in the pre-post period of 2019 (the counterfactual) from the 2020 lockdown effect to remove other determinants of species richness that are changing during the window.
To do this, we first select 2020 users with activity in at least 2 days before and after lockdown. Then we add all users from 2019 for the same days. These are different users but share similar characteristics.
Formally, we specify the following standard DID regression:
\[ SR_{ijdt} = \beta_{1} [Treatment_{t} \times Post_{t}] + \beta_{2} [Treatment_{t}] + \beta_{3}[Post_{t}] + X_{ijdt} + \mu_{d} + \gamma_{t} + \epsilon_{ijdt} \]
Where \(Treatment\) is a dummy for the year 2020 and \(Post\) is a dummy equal to one for observations after lockdown. \(\beta_{1}\) is the coefficient of interest and describes the change in species richness before and after March 19 in 2020 compared to the same difference in 2019. \(\beta_{2}\) describes the difference in the “before” groups (pre-intervention). \(\beta_{3}\) captures the time trend in the control (2019) group. \(X_{ijdt}\) is a vector of controls including trip duration. \(\mu_{d}\) is a set of city fixed effects and \(\gamma_{t}\) is a set of temporal controls including date and hour fixed effects.
| Diff-in-Diff Estimates (Top 20 cities) | ||
|---|---|---|
| Mar 24 Lockdown | Mar 22 Lockdown | |
| Treat x Post | 2.291*** | 2.500*** |
| (0.373) | (0.376) | |
| Duration | 0.106*** | 0.137*** |
| (0.004) | (0.005) | |
| Post | -1.611*** | -1.264*** |
| (0.405) | (0.385) | |
| Treatment | -11.520*** | -9.608** |
| (4.156) | (3.893) | |
| Num.Obs. | 4131 | 3870 |
| R2 | 0.293 | 0.350 |
| Adj.R2 | 0.289 | 0.347 |
| AIC | 24905.3 | 23124.3 |
| BIC | 25057.1 | 23274.6 |
| Log.Lik. | -12428.653 | -11538.158 |
| * p < 0.1, ** p < 0.05, *** p < 0.01 | ||